• 054350 - ELECTRON AND SCANNING PROBE MICROSCOPY

The course aims at providing a picture of the electronic probe microscopy techniques as general as possible, starting from the basics of the major techniques and examples of prototypical applications up to state of the art scientific cases. The main goal is to provide the student with the ability of assessing the feasibility and effectiveness of microscopic measurements to tackle a given problem. The couse will focus on the information that can be obtained (morphology, chemical contrast, short-and long-range structure, spectroscopy) and on the choice of the microscopic techniques that can be effectively employed to investigate a system in a given environment.

DdD1 - Knowledge and understanding
Upon passing the exam, the student knows the fundamentals of electron and scanning probe microscopies microscopy: she/he is able to draw the layout of a microscope and to comment its main assembly in terms of fundamental Physics (main phenomena and their order of magnitude).

DdD2 - Applying knowledge and understanding
Upon passing the exam, the student is able to select the most appropriate microscopical approach, within the range of techniques discussed, to address a standard problem in material microscopy and to discuss its advantages and disadvantages with respect to the other techniques.

DdD3 - Making judgements, Communication, Lifelong learning skills
Upon passing the exam, the student is able to read critically the scientific literature on microscopy: she/he is able to explain and discuss the techniques adopted by researchers and the evidences supporting their conclusions, eventually proposing a different approach to attain the same or and improved result.

Topics

- Probes with high spatial resolution and state of the art in research and applications.

- Interaction of free electrons and bound electrons with matter.

- Information obtained by using electronic probes.

a) Far field electron microscopy

- Introduction to electron microscopy

- Diffraction limit and ray optics

- The scanning electron microscope (SEM)

  - Interaction between electron and matter

  - Secondary electron contrast

  - Depth of field

  - Charging and other imaging artifacts

  - Back-scattered electron contrast

  - Auger and X-ray Micro-spectroscopy probes in SEM

- The transmission electron microscope (TEM)

  - Sample preparation

  - Bright and dark field imaging

  - The mass-thickness contrast

  - Direct and reciprocal space imaging

  - The diffraction contrast

  - The phase contrast

- The scanning transmission electron microscope (STEM)

  - Electron energy loss spectroscopy in STEM

- The time resolution in Electron Microscopy

  - Real time acquisition

  - Ultrafast pump-probe acquisition

b) Scanning probe microscopies

- Introduction to scanning probe microscopy

- Elements of a scanning-probe microscope

- Tip-sample forces

- Static AFM operation: constant height and constant force- Shift in the natural frequency of a harmonic oscillator under a force gradient

- Amplitude-modulation dynamic AFM operation

- Dynamic AFM operation: sensitivity in amplitude modulation, frequency-modulation techniques

- Noise and resolution in AFM

- Image analysis in AFM

- Magnetic force microscopy

- Other magnetic microscopy techniques

- Imaging artifacts in scanning probe microscopy

- Scanning near-field optical microscopy

- Super-resolution fluorescence microscopy

- Introduction to scanning tunneling microscopy

- Bardeen approach (time-dependent perturbation theory) to the tunneling current

- WKB approximation for the evaluation of the tunneling probability

- Atomic resolution with STM

- Scanning tunneling spectroscopy

Laboratory visits

Image analysis and practical use of research instrumentation.

Schedule

The couse will be held in the first half of the first term, from mid September to the beginning of November.

Notes

The range and detail of the course will be adapted to the level of the class during the course and may change significantly.

The course makes use of the formalism learned in the fundamental courses of Mathematics and of Physics at the Bachelor in Ingeneering Physics, although any other engineering course may satisfy the following minimal pre-requisites:

- Mechanics and Thermodynamics

- Electromagnetism

- Fundamentals of Quantum Mechanics

- Fundamental of electronics

The following topics are particularly relevant:

- Oscillations (forced, damped and multiple degrees of freedom)

- Ray optics (properties and defects of single lenses and multiple lenses)

- Interference and diffraction

The exam consists of an oral test in two parts of about half an hour each, one about Electron Microscopy and the other about Scanning Probe microscopy.

In each part:

- The student asked to present selected topics of the course, starting from  the fundamentals through increasing level of detail and difficulty.

- The student will be asked to select its microscopic technique of choice to address a scientific case and to comment about the limits of application, advantages, and disadvantages.

- The student will be required to briefly present a scientific paper, chosen in agreement with the teacher, where electron or SPM microscopies is the main investigation techniques. The presentation will be focused on the information attained by the use of microscopy and the technical approach adopted to obtain it.

textbook for the TEM and SEM section

Introductory reading on TEM, in French.

Advanced text on Electron Microscopy

Introduction to Scanning Probe Microscopy by a well-known manufacturer

Examples of applications